Control system for electric motors.



A. J. HALL.

CONTROL SYSTEM FOR ELECTRIC MOTORS.

APPLICATION FILED AUG-2. 1913.

' Ma-rfar F Confml/zr v Patented June 22,1915.

Cmf'm/ We JIS for WITNESSES: m NVENER ATTORN EY UNITED strA'rEs PATENT OFFICE.

ARTHUR J. HALL, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

CONTROL SYSTEM FOR ELECTRIC MOTORS Specification of Letters Patent.

. Patented June 22, 1915.

Application filed August 2, 1913. Serial N 0. 782,554.

To all 7W7)??? it may concern Be it known that, I, ARTHUR J. HALL, a subject of the King of Great Britain, and a resident of lVilkinsburg,-in the county of Allegheny and State of Pennsylvania, have invented a newand useful Improvement in Control Systems for Electric Motors, of which the following is a specification.

My invention relates to systems of control for electric motors, and it has special reference to overload trip devices that are employed in control systems for railway and vehicle motors.

One object of my invention is to provide a device of the above indicated character which shall be simple in construction, positive and reliable in operation, and adapted to eifect the interruption of the main motor pirtuitsunder conditions of abnormal overoa 7 Another object of my invention is to pro; vide an overload trip device having particu- 'lar adaptation for use in railway control systems of the multiple unit. type, which shall embody auxiliary switch members connected in the energizing circuits of the line switches ,and positively held in engagement, but which may be released to open the energizing circuits under abnormal conditions.

Another object of my invention is to provide a remotely controlled reset device associated with the above mentioned auxiliary switch members and having its energizing coil circuit normally open, but adapted to be closed under said predetermined abnormal conditions.

Another object of my invention is to provide means whereby the reset device is prevented from being energized except when the line switches are open.

I Heretofore, it has been customary to interlock the line switch energizing circuits with switch members carried by an overload electro-magnetic trip, in which case, the electrical connections of the interlock switches were not uniformly good and were affected by the current traversing the motor circuits. Furthermore, the energization of the reset coils could be effected at any time, which often resulted -in damaged coils by reason of their being subjected to current for long periods.

According to my invention I overcome these diificulties and provide an overload apparatus is not considered essential and,

consequently, only a sufiicient portion of the system is illustrated to enable a clear understanding of my present invention.

Referring to the drawing, the system shown comprises a supply circuit 1, a plurality of motors having armatures A and A and field magnet windings F and F a plurality of line switches LS and LS motor circuit switches M M G and JR, a transition switch J, a plurality of resistors R R R RR BB RR adapted to be connected in the motor circuits in both series and parallel operation, a plurality of switches adapted to short-circuit said resistors, a switch marked. Limit switch having its energizing coil in series circuit with one of said motors and adapted to be actuated in accordance with the current traversing the motor circuit, a hand operated switching device marked Master controller comprising a rotatable drum 3, and a set of stationary contact fingers 4 that are adapted to engage the drum along the position-indicating lines a, Z), c, and d for controlling the connections of the auxiliary energizing circuits, a resistor marked Control resistor connected between the supply circuit 1 and the ground G and provided with intermediate taps for the purpose of delivering a reduced voltage to the auxiliary control conductors, and an electro-responsive device marked Overload trip for interrupting the ener gizing circuits of the line switches LS and LS under abnormal current conditions.

All of the electrically operated switches LS LS M M R to BB inclusive, G,

terlock switches through which the auxiliary control circuits are interlocked, although, for

and an energizing coil 13.. A spring 14 is dis- I posed within a recess 15 in the stationary core 12 and normally acts against the movable core 11 and tends to effect the separation of the switch members 7 and 8 from their cooperating contact terminals 9. A movable member 16 is associated with a movable core 17 that is adapted to cooperate with. a stationary core 18, said cores being magnetized in accordance with the current traversing 'the' motor circuit through the agency of a coi 19 in circuit therewith. Under normal conditions, the-movable member 16 is held in engagement with the end of the movable member 6 by means of a spring 20 which is interposed between the member 16 and a stationary frame or bracket 21. A movable auxiliary switch member 22 is resiliently supported upon a stem 23 forming a part of the movable member 16 and is adapted to cooperate with a pair of stationary contact terminals 24 under abnormal current conditions to complete a circuit through coil 13. Normally, the switch member 22 is disengaged from its cooperating terminals so that the energizing circuit of the reset device is open.

Assuming the connection to be as shown, the operation of the system is as follows A switch termed control switch is first controller is moved into position a, thereby completing a circuit from the supply circuit 1 through said control switc upper conducting portions 3 of the master controller, andcontroller resistor to ground G. From the control resistor a circuit is completed including conductor 30, the lower conducting portions 3 of the master controller, conductor 31, coeperating switch members 7 and 9. associated with the reset device and energizing coil of switch LS marked LS coil to ground G. The LS -coil is, of course, directly associated with the LS switch but is shown as separated therefrom in the diagram for purpose of clearness and simplification thereof. The switch LS is, therefore, closed. Immediately subsequent to this operation, a circuit is completed from conductor 31 including interlock switch M out, energizing coil of switch JR, interlocking switch J-out and interlock switch LS in to the control reing F resistors-R R R switch JR, re-

accomplished the closure of these switches, a

main motor circuit is completed from the supply circuit 1 through switch 33, conductor 34, energizing coil 19 of the overload trip and thence to. ground G through the following devices,-'s witch LS resistor R, switch M armature A field magnet windsistors BB RR, RR armature A field magnet winding F and limitcoil of the limit switch, Energy is thus supplied to the two series connected driving motors through all of the resistors and the said motors are, therefore, started into operation at slow speed.

In order to increasethe speed of operation, the. master controller is moved to its second notch marked b thereby completing an energizing circuit from the master controller through the limit switch, provided, of course, that the motor currentis not sufliciently great to cause said switch to disengage its contact members, and thence through interlock switch LS out, cooperating switchmembers 8 and 9 associated with the reset device, and the energizing coil marked LS -coil of the switch LS to ground. Upon the completion of this 100 circuit, switch LS is closed if. normal circuit conditions obtain, theoperation being governed by the action of the limit switch in accordance with the usual practice. The

closure of switch LS short circuits resistor R and allows the motors to increase in speed.

Resistors R to RR are then short-circuited in accordance with the action of the limit switch, although no description thereof will be given.

By moving the master controller consecutively to positions 0 and ti, the motor connections are changed over to parallel arrangement with all the resistors R to RR in circuit, after which the resistors are again automatically short circuited until the motors are operated in parallel directly across the line. i

It will be noted that the line switches LS and LS constitute the circuit interrupters of the system, and their energizing coils are interlocked with switches 7 and 8 of the rereleasing the movable, member 6 and asso-v ciated contact members 7 and 8, and also causing the switch member 22 to engage its contact terminals 24. As soon as the memswitches LS and LS are caused to .open

v to the reset coil through the control' the main motor circuit. Inasmuch as the member 16 has been raised to its upper position, the member 6 prevents it from again dropping and thus maintains the switch members 22 and 24in engagement, making it possible to energize the reset coil 13 by moving the control switch to its right position. In this event, energy is supplied switch resistor 35, coil 13 and switch members 22 and 24 to ground G. Upon the energization of the reset coil 13, its movable core 11 and member 6, together with the switch members 7 and- 8, are moved to the left, thereby permitting members 16, 17

and their associated switch member 22 to drop to their normal positions. At the same time, the switch members 7 and 8 again cooperatively engage their contact terminals 9, thereby permitting the normal operation of the control system in the manner hereinbefore set forth.

Attention is directed to the fact that the auxiliary switch members 7 and 8 are maintained in engagement with their contact terminals 9 under a definite and positive pressure which is unaffected by the current traversing the coil 19 of the overload trip, and, as long as the energizing circuits of the line switches LS and LS are completed, it is impossible to energize the reset coil by reason of the interruption of its circuit at the switch members 22 and 24. The reset coil, therefore, may be energized only after the overload trip has operated and then, only for the short interval of time that is required for the actuation of the movable parts of the reset device.

I have shown and described my invention in connection with an automatic multiple unit control system merely for illustrative purposes and not with the intention of being restricted to such a type of system.

Various modifications in the arrangement of apparatus and circuit connections maybe effected without departing from the spirit and scope of my invention.

I claim as my invention:

1. A switching device comprising stationary and movable magnetizable cores, an en ergizing coil therefor, a switch member associated with said movable core, a latch adapted to mechanically restrain said core and switch member in their closed positions, an electro-responsive device for releasing said latch, and a switch member associated theregagement and adapted to release them under predetermined conditions and an auxiliary switch member associated with said electroresponsive .means for closing the circuit of said electromagnet under said conditions.

3. A switching device comprising relatively movable cooperating switch members included in a circuit to be controlled, means normally tending to disengage said members, and means for opposing said disengaging means, of means adapted to retain said switch members in engagement and dependent upon abnormal circuit conditions for permitting their separation, and means associated with said retaining means for effecting the operation ofsaid opposing means.

4. A switching device comprising cooperating switch members included in a circuit to be controlled, resilient means for separating said switch members, a latch for preventing said separation under normal conditions, an electromagnet for governing the operation of said latch in response to current conditions of an electric circuit, switch members associated with said latch and normally disengaged, and a resetelectromagnet in circuit with said last named switch members and adapted to be energized for effecting the engagement of the switch members in the circuit to be controlled.

5. The combination with an electric c1rcuit and an electrically operated switching device included therein, of an auxiliary switching device included in the energizing circuit of. said electrically operated device and normally restrained in its closed position, an electro-responsive device in sald electric circuit for governing the operation of said auxiliary switching device in accordance with current conditions of said electric circuit, electro-magnetic means for closing said auxiliary switching device, and means for limiting the duration of energization of said electromagnetic means. H

6. In a control system, the combination with an electric motor, a circuit interrupter in circuit therewith, an electromagnetic device dependent upon said motor current and having normally separated contact members, a latch for restraining said device in 1ts closed position and cooperating switch members associated with said latch and governing the operation of said circuit interrupter, of an electromagnet for releasing said latch and having its energizing coil in circuit with the switch members of said electro magnetic device.

7. The combination with an electro-magnetic overload device having normally separated auxiliary contact members, of means for latching said "device in its closed position, an electro-magnet forreleasing said latch having its energizing coil in circuit with said auxiliary contact members.

The combination with an electric circult, and an electro-responsive switching de vice influenced by the current in said circuit and normally adapted to occupy its open position, of mechanical means for positively latching said switching device in its closed position and a releasing electro-magnet associated with said mechanical latching meansfor withdrawing said means and having an energizing coil interlocked through said switching device whereby said coil is energized only for a predetermined short interval of time.

9. The combination with cooperating switch members normally held out of engagement, and a latch for retaining said switch members in engagement when once effected, of electrical means for releaslng said latch and having its energizing circuit interlocked with said switch members and completed only when the switch members are in cooperative engagement. I

Intestimony whereof, I have hereunto subscribed. my name this 26th day of July,

- ARTHUR J. HALL.

Witnesses L. G. RILEY, B. B. HINES. 

